US3730299A

US3730299A - Elevator control system

Info

Publication number: US3730299A
Application number: US00082476A
Authority: US
Inventors: I Inuzuka; K Watanabe; T Yuminaka; T Iwasaka; T Ochi
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1969-10-24
Filing date: 1970-10-20
Publication date: 1973-05-01
Anticipated expiration: 1990-05-01
Also published as: GB1305960A; CA933685A

Abstract

In a plurality of elevator cars serving a plurality of floor landings, an elevator control system in which the response of a preceding car to hall calls from predetermined forward floors is limited when the space between said preceding car and a succeeding car is shortened.

Description

[541 iELEVATOR CONTROL SYSTEM [75] Inventors; Isao lnuzuka; Kikuo Watanabe;

Takeo Yuminaka; Tatsuo lwasaka,

all of Katsuta; Toshio Ochi, Hitachi, I

. all of Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: Oct. 20, 1970 21 Appl. No.: 82,476

[30] Foreign Application Priority Data [451 May 1, 1 973 [56] References Cited UNITED STATES PATENTS 3,614,997 10/1971 Lusti 3,519,106 7/1970 Kirsch 1 87/29 Primary Exarhinen-Bemard A. Gilheany Assistant Examiner-W. E. Duncanson, Jr. Attorney-Craig, Antonelli and Hill [57] ABSTRACT In a plurality of elevator cars serving a plurality of floor landings, an elevator control systemin which the 12 Claims, 11 Drawing Figures DEV/CE- 0m. 24, 1969 Japan .....44/s4719 Dec. 8, 1969 Japan ..44/97882 Dec. 8, 1969 Japan ..44/97ss3 [52] US. Cl. ..l87/29 R [51] Int. Cl. ..B66b 1/20 [58] Field of Search 1 87/29 P05/770/V FA ADWl/VC/NG DEV/CE SPACE Q? 1 0575070,?

SPACE DEC/S/ON DEV/CE Patented May 1, 1973 8 Sheets-Sheet AQUA/ AND AND AND

AND

A/UAZ AND ' All/45 a AND INVENTORS :sao iNuZUJAQ Kmuo wa aNngE,

TmAEO wummman; TFWauo wRsFmH RND TO$H\O O(.

BY Chai MM EW 1 XML ATTORNEYS The present invention relates to an improved control system for efficiently operating a plurality of elevators, especially a number of elevators installed in a building, in accordance with passenger traffic.

When a plurality of elevator cars serve a plurality of floors, it is necessary to prevent the elevator cars from bunching namely, moving together. In other words, the elevators must be operated, maintaining an appropriate, if not equal, space between them so that passenger waiting time for the arrival of an elevator becomes almost equal for each floor.

At ordinary times when the up demand almost equals the down demand, it is generally recommended that elevator cars be distributed at equal intervals among all.

floors. For this purpose, a time dispatching device for starting the elevator cars atreasonable time intervals (or space intervals on some occasions) from the bottom terminal is provided. After operating the elevator cars in response to hall calls from intermediate floors for some time, the spaces between the elevator cars are liable to become unbalanced, resulting in bunching. The situation becomes especially bad during downward travel and, to overcome this, the installation of another time dispatching device on the top terminal has been suggested. But this furnishes no satisfactoryv solution, because with such a method, the start of a succeeding car is intentionally delayed at the top terminal when the space between it and a preceding elevator car is unreasonably shortened, lengthening the round trip time of a car, and as a result, adversely affecting the operating efficiency of the cars in general. ()nce a bunching of cars is developed, the situation cannot be improved .until either terminal, top or bottom, is reached, leading to a longer passenger waiting time at some inconvenience to waiting passengers.

It is not merely during daylight hours that a bunching of cars develops. During office-leaving hours when the down traffic is heavy due to many down calls, for example, more cars are involved in downward movement than in upward movement. The bunching will cause a long passenger waiting time in this case, too. Therefore, it is desirable that the cars are not distributed uniformly among the floors, but move up at greater intervals than when moving down.

Accordingly, it is an object of the present invention to render as uniform as possible the passenger waiting time on each floor by controlling the operation of cars in accordance with the traffic so as to run them at reasonable intervals. 7

Another object of .the present invention is to improve the operating efficiency of cars by. correcting a bunched state without affecting smooth operation of the cars.

Still another object of the present invention is to advantages will be made apparent by the detailed descn'ption taken in conjunction with the accompanying I drawings, in which:

. FIG. 1 lSa'blOCiK. diagram showing an embodiment of the system according to the present invention;

FIG. 2 is a detailed circuit diagram showing an example of a space detector according to the invention;

FIG. 3 is a detailed circuit diagram showing a space decision device according to the invention;

FIG. 4 is a detailed circuit diagram showing an example of a position advancing device according to the in vention;

F IG. 5 is a detailed circuit diagram showing an example of a service decision device for hall call according to the invention;

FIG. 6 is a diagram for explaining the operation of cars by using the system of the present invention;

FIG. 7 is a detailed circuit diagram showing another embodiment of a service decision device for hall call;

FIG. 8 is a circuit diagram showing an indicator;

FIG. 9 shows still another embodiment of the present invention;

FIG. 10 is a circuit diagram showing a device for detecting the number of calls; and

FIG. 11 is a circuit diagram showing a service floor limiting device according to the invention.

Referring now to FIG. 1, the following explanation will be made of a hypothetical case in which three elevator cars -A,;B and C serve a building with ten floors. Although FIG. 1 shows the control system for only car A, similar systems are also provided for cars B and C. The space detector DA receives as an input the position signal FA for car A together with signals FE and FC for carsB and C respectively to detect the spaces between car A and succeeding cars, and it produces as an output the space signalSSA. The space decisiondevice EA is supplied with the adjusting signal K for position advance and said space signal SSA and produces the position advancing signal PSS which is applied to the position advancing device GA. The position advancing device GA advances the position signal FA of car A by the amount specified by the position advancing signal PSS and thereby produces the provisional position signal fa. This provisional position signal fa for car A together with the provisional position signals fb and fc for cars B and C are applied to the service decision device for hall call MA which, when supplied with a hall call signal HC, decides whether car A should respond to it or not. If it responds, the response signal NA is produced, thereby announcing that car A is stopping at the floor from which the signal HC has come. Incidentally, the signal fa is also applied to service decision devices MB and MC (not shown in the drawing) for cars B and C respectively. I

Said position signals may indicate either a floor number or a distance. For practical purposes, however,

the indication of a floor number is recommended. This kind of signal which shows the actual car location is called a physical position signal. But when the cars stand still at any of the floors, such floors (which agree with physical positions) may be indicated and while running, the floor in advance of a physical position may be indicated, as a position signal. In the latter case, the fourth, fifth or sixth floor, for example, may be indicated when the car is going up through the third floor at a low, middle or high speed respectively. This holds true in the case where the car position is shown by distance.

In a typical elevator control system, a rising car responds to hall calls for upward movement, while a descending car responds to those calls for downward movement. That is to say, an elevator car responds to up callsfrom the first floor (bottom terminal) -to upper terminal floor in order, and-after reaching the top floor, it responds to the down calls from the top floor to lower terminal floor in order. Floors ahead of a moving car are called forward floors and calls from the forward floors, forward hall calls, while floors behind a moving car are called back floors and calls from back floors, back hall calls. For example, if a car passing up through the fifth floor receives an up call from the sixth floor, it is a forward hall call, and if it receives a call from the third floor, 'it is a back hall call. The reverse is true in case of downward travel.

An elevator car is usually made to respond to forward hall calls positioned in advance of the position indicated by the position signal for that car. But in a special case where the car is made not to respond to forward hall calls for a specified zone, its provisional position is advanced. The nearest floor, the hall call from which a car can actually respond to is hereinafter called the provisional position. In other words, when response to forward hall calls is not limited, the provisional position agrees with the position signal, whereas it leads the position signal if hall calls from some floors are neglected.

Assume now that car B is succeeding car A. Then, spacedetector DA detects the difference between the position signals FA and PB indicating the positions of cars A and B respectively. Whether the space between cars A and B is reasonable or not is decided by the space decision device EA. The determination of a reasonable space depends on various factors. Under normal traffic conditions in which cars are distributed uniformly among all the floors, the reasonable space FS will be (Ns 1) x 2 N c (Ns: number of service floors) (Nc: number ofcars) It is desirable that the value of reasonable space FS be adjusted according to the prevailing traffic conditions including the number of passengers in each elevator car, the floors they intend, the round trip time of each car and the number of hall calls from each floor.

When the space between cars A and B is equal to or near the reasonable space FS, the position advancing signal PS8 is not produced and therefore the provisional position signal fa of car A agrees with the position signal FA. If, however. the actual space becomes shorter than a predetermined value. the position advancing signal PS8 is produced, thereby to advance the provisional position signal fa of car A by the required number of floors ahead of the position signal FA. lncidently, it is recommended that the amplitude of the position advancing signal PSS should be determined, taking into consideration the difference from the reasonable space, the number of passengers in car A, the round trip time of each car, etc. This purpose is served by the position advancing device GA which produces the provisional position signal fa positioned by a required amount ahead of the position signal FA depending on the position advancing'signal PSS. If car C is preceding car A, the service decision device MA is actuated in such a manner that car A responds to the hall call signal HC produced between the provisional position signals fc and fa. Then, the response signal NA is produced and a hall indicator is lit, informing waiting passengers of the scheduled arrival of car A. Accordingly, car A starts to be decelerated when it reaches the retarding point. I

A detailed circuit diagram of the space detector DA of FIG. 1 is shown in FIG. 2. When car A set for upward movement stays at the first floor, the position signal FIUA is produced. Similarly, when car A which is set for upward movement stays at any of the second to ninth floors, the position signals F2UA to F9UA are produced respectively. Conversely, when car A which is set for downward movement stays at any of the second to 10th floors, the position signals F2DA to F10DA are produced respectively. The space detectors DB and DC (not shown) for cars B and C respectively operate on the same principle, producing the position signals FlUB to F9UB for upward movement and FZDB to F10DB for downward movement of car B, and position signals F lUC to F9UC for upward movement and F2DC to F10DC for downward movement of car C, as required.

Each of the position signals F 1 UA to F9UA and F 2DA to F10DA constitutes an input to the OR circuits OlUAl to O9UA1 and O2DA1 to O10DA1 respectively. The position signals for cars B and C indicating the same direction of car movement and the same floor are combined and applied to the OR circuits O1UA2 to O9UA2 and O2DA2 to O10DA2. For example, signals FZUB and F2UC are applied to OR circuit O2UA2 in combination. The inhibit elements I lUA to I9UA and IZDA to l10DA correspond to the position signals F lUA to F9UA and F2DA to F10DA respectively. And to the input terminals of those inhibit elements are ap plied the outputs of said OR circuits OlUAl to O9UA1 and O2DA1 to O10DA1 respectively. On the other hand, the outputs of said OR circuits OlUA2 to O9UA2 and O2DA2 to O10DA2 are applied to the respective inhibit terminals. The outputs of all the inhibit elements are connected together through the resistors rlUA to r9UA and r2DA to rlODA and are grounded through a common resistor rA. The space signal SSA is picked up from the ends of the common resistor rA. The inhibit elements are arranged in a ring in the order of llUA, l2UA, I9UA, llODA, l9DA IZUA and llUA, the outputs thereof being respectively applied to the OR circuits OlUAl to O9UA1 and O2DA1 to Ol0DAl.

Now, suppose car A is in upwards movement at the eighth floor, that car B is in downwards movement at the second floor and that car C is in downwards movement at the fifth floor, namely, car A is followed by car B. In this case, position signals F8UA, F2UB and FSDC are produced. First, position signal FSUA for car A triggers the OR circuit O8UA1, whereby the inhibit element ISUA produces an output. This signal is applied to the OR-circuit O7UA1 (not shown) which accompanies the inhibit element l7UA (not shown), which is thus energized. In like manner, inhibit elements I6UA, ISUA, I4UA and I3UA (not shown) are energized. The output of inhibit element I3UA is ap- 02UA2 by the position signal FZUB. As a result,

signals are applied to the resistors r3UA to, r8UA. Under these condition, the voltage across the resistor rA is: i

To nTo rnm-ir n I where r is the resistance value of resistors rlUA to r9UA and r2DA to rDA, n is the number of inhibit elements which are producing an output and r,, is the 1 value of the common resistor rA. If the relation r r is set,

SSA (nr lr) and therefore a signal proportional to the number of inhibit elements energized is obtained. In the abovedescribed example, n 6. Therefore, a six-floors space (eighth floor to second floor) is detected between car A and the succeeding car B.

A detailed circuit diagram showing an example of the space decision device EA is illustrated in FlG. 3. The output signal SSA of the space detector DA is applied to the adder ADDA which consists of the operational amplifier OPA, feedback resistor RFA, I feedback capacitor CA and input resistors RlA to R4A. The space signal SSA, the signal CWA corresponding to the number of passengers in the car A, a signal representing the round trip time RTT and one representing the number of hall calls NOHC are applied respectively to input resistors RlA, R2A, R3A and R4A. Consequently, the output of the adder ADDA is:

where r, to 7 and rfa are the resistance values of the resistors RlA to R4A and RFA respectively. The output of said adder ADDA is compared with the reference voltages V, to V from the reference-voltagesetting resistors RllA to Rl4A respectively by the comparators CM 1A to CM4A, and if a reference voltage is higher than or equal to the output of the adder ADDA, a corresponding comparator produces an output. ln actual practice, since the reference voltage is positive and the output of the adder ADDA is negative, the comparator produces an output signal when the sum of the two inputs is zero or positive. The inhibition elements lCMOA to ICM3A are for producing an advancing signal 'PSS. Particularly, the inhibit element lCMOA produces a zero-flooradvancing signal EOA (signal FA is made to agree with signal fa), the inhibit element lCM lA produces a 1-f|oor advancing signal ElA, the inhibit element lCMZA produces a two-floor advancing signal EZA and the inhibit element ICMBA produces a three-floor advancing signal EBA. The comparator CM4A produces a four-floor advancing signal 54A. Incidentally, when a given inhibit element is supplied with an input signal, the inhibit terminal of an inhibit element in the preceding stage receives an input through an appropriate-OR circuit among those symbolized by OCMlA to OCM3A so that two or more inhibit elements are not energized at the same time. A

Explanation will now be made of the operation of the above-described device. For convenience of explanation, let us suppose that the values-r to r, are infinite, that is to say, the only output of the adder ADDA is the space signal SSA. Also assume that the reference volt ages V to V, are set at values corresponding to the five-, four-, threeand two-floors respectively.

In a hypothetical case where there is a space of eight floors between car A and the succeeding car B (that is to say, an eight-floors signal is produced as the space signal SSA), the reference voltage and the output of adder ADDA applied to the comparator CMlA are respectively 5 and 8, and therefore no output is produced from said comparator. This is also the case with the outputs of the comparators CM2A to CM4A. As a consequence, only the inhibit element lCMOA produces an output and applies the signal EOA to the position advancing device GA. This is the very case where, as mentioned above, the provisional position signal fa is equal to the position signal FA.

In the next .place, the space signal SSA indicates four-floors, the comparators CMlA and CM2A produce an output signal. In this case, the inhibit eleinent lCM2A produces an output and supplies the twofloors advancing signal E2A to the position advancing deviceGA, whereby the provisional position signal fa for car A becomes equal to FA 2 as indicated by the number of floors. When the comparator CMZA produces an output, the inhibit terminals of the inhibit elements ICMlA and lCMOA receive a signal through the OR circuits OCMZA and OCMIA respectively, thereby cutting off the respective inhibit elements.

The detail of a circuit of the position advancing device GA is shown in FIG. 4. This illustrates an example in which the provisional position signal fa indicates any of the first to ninth floors foran upgoing car. The principle disclosed, however, also applies toa downgoing car.

The position signals F9UA to FSUA forcar A are applied to the AND circuits A9UA1 to A9UA5 (A9UA3 to A9UA4 are not, shown in the drawing) respectively. As another input to these AND circuits, the advancing signals EOA to E4A from the space decision device EA are applied respectively. The output of each AND circuit is applied to the OR circuit Of9Ua which generates a provisional position signal f9Ua. In like manner, the position signals F8UA toF4UA for car A are applied to the AND.circuit A8UA1 to A8UA5 respectively and the output of each of said AND circuits is applied to the OR circuit Oi8Ua. The position signals F 1 UA to F SDA are applied through the AND circuits AlUAl to -AlUA5 respectively to the' OR circuit OflUa. The same can be said of the other position signal producing circuits which are omitted from the drawing.

If car A which stays at the first floor ready for starting upward is too distant from the succeeding car B, the position signal F lUA and position advancing signal 50A for car A are produced. As a result, the AND circuit AlUAl is energized and the OR circuit OflUa produces an output. In other words, the provisional position signal fl Ua in this case agrees with the position signal F lUA, both indicating the first floor and upward movement.

As another example, assume that an upgoing car A which stops at the fourth floor is too near to the succeeding car, thereby producing the advancing signal E4A. Then the position signal F4UA is also produced, whereby the AND circuit A8UA5 produces an output, energizing the OR circuit Of8Ua. Therefore, the position signal F4UA for car A is advanced by four floors into the provisional position signal fSUa (eighth floor).

In FIG. 5, a detailed circuit diagram of an example of the service decision device MA for hall calls is shown; The inhibit elements IlUa, I2Ua, I9Ua, llDa, I9Da I2Da are provided corresponding to the provisional position signals flUa, fZUa f9Ua,

fl0Da, f9Da t2Da respectively. Said inhibit elements receive an input signal through the OR circuits OflUal to Of9Ual and OfDal to Ot2Dal respectively, the inhibit terminals thereof receiving an inhibit signal from the OR circuits OflUa2 to Of9Ua2 and Ofl0Da2 to Of2Da2 respectively. The provisional position signals flUa to f9Ua and flODa to f2Da are applied to the OR circuits OflUal to Of9Ual and OflODal to Of2Dal respectively, each of said OR circuits being supplied with an output from an inhibit element in the previous stage. The inhibit elements are thus in ring-connection with each other. The output of the inhibit element I10Da is applied to the OR circuit Of9Dal which accompanies the inhibit element I9Da. The outputs of the inhibitelements are applied to the AND circuits AlUa to A9Ua and A10Da to A2Da respectively. These AND circuits are also supplied with theeachfloors hall call signals HCIU to HC9U and l-lClOD to HCZD respectively.

Suppose an upgoing car A is at the provisional position of the second floor and that the preceding upgoing car C is located at the provisional position of the ninth floor (both cars are going upward), with the provisional position signals f2Ua and f9Uc produced. The OR circuit Of2Ua1 is energized, causing the inhibit element I2Ua to produce an output. The output of the inhibit element I2Ua is applied to the AND circuit A2Ua and at the same time to the OR circuit Of3Ual (not shown) in the following stage, thereby to energize the inhibit element I3Ua. Similarly, the other inhibit elements (not shown) are energized, including the inhibit element I8Ua whose output is applied to the OR circuit Of9Ual in the following stage. The inhibit element l9Ua is not energized because its inhibit terminal receives an input through the energization of the QR circuit Of9Ua2 which is caused by the position signal f9UC for car C. As a result, the inhibit elements I2Ua to I8Ua are energized, supplying an input to the corresponding AND circuits A2Ua to ASUa respectively. Therefore, if there are any of the hall call signals HC2U to HC8U generated at any of the second to eighth floors for upward travel, a corresponding AND circuit produces an appropriate signal out of the signals N2UA to NSUA, indicating that car A will accept such'a hall call. These response signals N2UA to N8UA cause a hall indicator to be lit up, announcing the expected arrival of car A to the waiting passengers. Also, a deceleration command is issued when car A reaches a retarding point, thereby to stop the car. In this way, car A also responds to hall calls from the floors behind the provisional position of car C.

The operation of elevator cars according to the present invention is illustrated in FIG. 6 which shows the three cars A, B and C serving a lO-storied building.

Car A is in upwards movement at the third floor, car B is in upwards movement at the first floor and car C is in downwards movement at the seventh floor. The position signals F3UA, FlUB and F7DC are produced. Also assume that hall calls HC4U and HC8U are issued from the fourth and eighth floors respectively. For convenience sake, let us consider the case in which traffic is balanced and the cars are to be uniformly distributed among all the floors. The value of the reasonable space F S is obtained from the following formula:

FS= =6 (floors) The space of two floors between cars A and B as shown in FIG. 6 is detected by the space detector DA and the space signal SSA indicating two floors is produced. Then, the space decision device EA is energized to produce an advancing signal PSS indicating four floors. As a result, the position advancing device GA advances the position signal F3UA of car A by four floors and produces the provisional position signaltVUa showing that it can respond to hall calls from the seventh floor and up. Such a provisional position of car A is shown by the dotted lines in FIG. 6. Car A accordingly neglects an up call from the fourth floor while continuing its upward travel, until theeighth floor where it responds to the up call signal HC8U. That is to say, in this example, car A responds to up calls from any of the seventh to ninth floors and also to down calls from any of the eighth to 10th floors, which are all back hall calls for car C. Car B, by contrast, responds to up calls from any of the second to sixth floors. For this reason, while car B is decelerated and stops at the fourth floor in response to the hall call HC4U, car A rapidly goes up to the eighth floor, thus widening the space between cars A'and B back to a reasonable length.

In the above device, if car A is operated in such a way as to respond to all the hall calls between its provisional position and that of the preceding car C, it is likely that cars A and B will become too close to each other when there are many hall calls to be responded to by car A and there are few to be responded to by the succeeding car B. This is an important problem worth considering in view of the fact that if waiting passengers are informed of the very car expected to serve them at the time of hall calls, that car cannot help stopping at the floors in question.

The detailed circuit diagram of a service decision device for hall call obviating the above-mentioned defects is shown in FIG. 7. In this improved device, when the space between a given car'and the succeeding car is shortened too much, the provisional position of the preceding car is advanced and also the-response of the preceding car to ball calls from the floors ahead of the provisional position, thereby to further maintain :a reasonable space between the cars and to render the passenger waiting time uniform. In such a device, the inhibit elements llUa, I2Ua, I9Ua and ll0Da, I9Da, I2Da and "U21 are provided corresponding to the provisional position signals flUa, f2Ua, f9Ua and f 10Da, i9Da, f2Da and f1 Ua respectively for car A. Said inhibit elements are supplied with an input signal through the OR circuits OflUal to Of9Ual and OflODal to OtZDal respectively. Also, inhibit signals are applied to their inhibit input terminals through the '9 OR circuits OflUaZ to Ot9Ua2 and OflDa2 to Of2Da2 respectively. Each of the OR circuits OflUal to Of9Ual and OflODal to Of2Da1 is supplied with a corresponding provisional position signal out of the signals flUa to f9Ua and fl0Da to f2Da together with the output of an inhibit element in the preceding stage. Thus the inhibit elements and OR circuits are in ringconnection with each other. In FIG. 7 the output of the inhibit element IDa is applied to the OR circuit Of9Dal accompanying the inhibit element I9Da. The output of each inhibit elements is applied to a corresponding element among the AND circuits AlUa to A9Ua and A10Da to A2Da which are also supplied with hall call signals HClU to HC9U and HClOD to I-IC2D together with the output of the NOT circuit PN. The outputs of said AND circuits are applied to the memory elements MlUa to M9Ua and MlODa to M2Ua respectively, thereby to set them.

On the other hand, when car A begins to decelerate at any of the floors, these memory elements are reset en masse by the deceleration signal SDa. In other words, with the deceleration of car A, the pulse element Pf produces a pulse of width t thereby energizing the OR circuits 100a and OlUa. Then, the OR circuits O9Da to O2Da and O2Ua to O9Ua are energized in that order, resetting all the memory elements.- The delay elements TD and TU produce an output at a predetermined time t after receiving an input and stop the output as soon as the input ceases.

As is clear from the above description, an output produced by any of the memory elements triggers the OR circuit OR and, the predetermined time t (t t,) after that, the delay element T produces an output. Then, the NOT circuit PN stops producing an output and therefore the AND circuits AlUa to A9Ua and A 10Da to A2Da are not energized even if there are hall calls. As a result of the energization of the memory elements, the service indication relays RlUa to R9Ua and R10Da to R2Da are excited and, closing the contacts as shown in FIG. 8, announce that car A is stopping at the calling floors. This announcement is done by the indication lamps LlUa to L9Ua and L10Da to L2Da respectively.

Let us now assume that car A is at the provisional position of the second floor and the preceding car C at the provisional position of the ninth floor. If both are going up, provisional position signals f2Ua and t9Uc are produced. The OR circuits Of2Ua1 is energized to cause the inhibit element l2Ua to produce an output. The output of this inhibit element l2Ua is applied to both the AND circuit A2Ua and the OR circuit Of3Ual in the next stage (not shown) at the same time, thereby to energize the inhibit element I3Ua. The other inhibit elements (not shown) are similarly energized, including the inhibit element I8Ua whose output is applied to the OR circuit Of9Ual in the next stage. The inhibit element in this stage, however, is no longer energized since the OR circuit Of9Ua2 is energized by the position signal t9UC of car C, applying an input to the inhibit terminal of said inhibit element I9Ua. Therefore, only the inhibit elements l2Ua to I8Ua are energized-to supply an input to corresponding AND circuits A2Ua to A8Ua respectively. Also, all the memory elements are reset, de-energizing the OR circuit OR and energizing the NOT circuit PN. Therefore, if any of the hall ample, there is'a forward hall call from the second floor 'for upward, the signal HCZU is produced, causing the AND circuit A2Ua to produce an output. Then, the memory element M2Ua is set, the service indication relay RZUa is energized and the indication lamp L2Ua is lit through the contact R2Ual, announcing that car A is stopping at the second floor landing.

The memory element M2Ua issues a deceleration command when car A reaches the retarding point of the second floor andalso producesan output signal for energizing the OR circuit OR and de-energizing the NOR circuit PN. Then, one of the inputs to each of the AND circuits A2Ua to A8Ua becomes zero, thereby causing the other memory elements to neglect any succeedinghall calls from any of the third to eighth floors for up travel. If the succeeding car approaches car A while car A is serving the hall call from the second floor, car A responds only to those hall calls beyond its newly-set provisional position; t

Assume, for example, that hall calls are given from the fourth, seventh and eighth floors for upward travel after the memory element M2Ua is energized and before its resetting due to the decision made to serve the second floor. When car A starts'decelerating to stop at the second floor, the deceleration signal SDa is applied to the OR circuit O9Da, supplying a reset signal to the memory element M2Ua. If, at this time, the space between car A and the succeeding car remains unchanged, the provisional position of car A also remain at the second floor. Therefore, the AND circuit 4Ua (not shown) immediately produces an output and the memory element M4Ua (not shown) is set. The memory elements M7Ua'and M8Ua are not energized since they receive a reset signal due to the output of the AND circuit A4Ua. In this way, car A is temporarily exempted from hall calls excepting those from the nearest forward floor.

As another example, suppose the provisional position of car A is advanced up to the fifth floor because of the approach of the succeeding car, when a reset signal is applied to the memory element M2Ua. Then, the provisional position signal f2Ua disappears and is changed into the signal fSUa, whereby car A no longer responds to the hall call from the fourth floor. Instead, the hall call from the seventh floor, the new nearest forward floor energizes the memory element M7Ua, thereby stopping car A at the seventh floor. As a consequence, car A which has not responded to the hall call from the fourth floor widens the space between it and the succeeding car, the hall call from the fourth floor being served by the succeeding car.

It will be understood from the above that, according to the invention, when two or more forward hall calls from beyond the provisional position are registered, those hall calls excepting the nearest one are temporarily exempted. Therefore, a preceding car with many forward hall calls need not respond to them all except one, and so a reasonable space is maintained between it and the succeeding car even if that succeeding carhas only afew forward'hallcalls'to be served. This interlocking system is released when the preceding car has stopped in response to a hall call, and as a result it is allowed to respond to the previously neglected hall calls, if any. i

If the succeeding car is too near to the preceding car,

' hall calls which originally might have to be served by in FIG. 9. Also, in this embodiment, when the space between a preceding car and a succeeding car becomes unreasonably small, the provisional position of the preceding car is advanced with respect to the position indicated by a position signal for the preceding car and at the same time its response to forward'hall calls beyond its provisional position is limited in order to maintain a reasonable interval between the succeeding car, thereby rendering the waiting time uniform.

In FIG. 9, the provisional position signals flUa to f9Ua and flDa to f2Da for car A are applied to the OR circuits OlUa to O9Ua and ODa to O2Da respectively. Further, in this embodiment, a provisional position signal is applied also to OR circuits corresponding to provisional position signals indicating two floors ahead.- For example, the provisional position signal fSUa is applied also to the OR circuits O9Ua and O10Da corresponding respectively to the ninth and 10th floors in addition to the OR circuit O8Ua. Moreover, a provisional position signal is applied to the OR circuits corresponding the provisional position signals for three and four floors ahead through appropriate ones among the AND circuits AlUa2 to A9Ua2 and A10Da2 to A2Da2 and also AND circuits AlUa3 to A9Ua3 and A10Da3 to A2Da3 respectively. The provisional position signal f8Ua, for example, is applied through the AND circuits A9Da2 to A8Da3 to the OR circuits O9Da to O8Da respectively. In other words, an OR circuit corresponding to each provisional position signal receives, in addition to said provisional position signal, the provisional position signals one and two floors previous to said OR circuit, and also, through the AND circuits, the provisional position signals three and four floors previous to said OR circuit. As will be described later, said AND circuits receive signals N1 and N2. The outputs of the OR circuits OlUa to O9Ua and Ol0Da to O2Da constitute an input to the AND circuits AlUal to A9Ual and A10Da1 to A2Da1 respectively. To these AND circuits are applied the hall call signals HClU to HC9U and I-I CIOD to HC2D and the running signal STPA which stops being applied when car A comes to a stop. The outputs of said AND circuits are applied to the memory elements MlUa to M9Ua and M l0Da to M2Da respectively for setting them. To these memory elements are applied the signals SlUa to S 9Ua and S10Da to S2Da respectively for resetting them, when car A begins to decelerate to serve the corresponding floors, and as a result their outputs disappear. When the memory elements are energized, the service indication relays RlUa to R9Ua and R10Da to R2Da are excited and the conof car A through the hall indicators LlUa to L9Ua and L10Da to 'LZDa respectively.

A device for detecting the hall call number HCN is shown in FIG. 10. Hall call signals I-IClU to I-ICIOD from the respective floors are applied through the resistor r, to the common resistor r on the same principle as that in the case of FIG. 2. Although not shown in the drawing, the cage call numbers CCNA to CCNC for cars A to C can be detected by use of a similar device.

FIG. 11 shows an example of the service floor limiting device which generates signals N1 and N2. Signals indicating a hall call number HCN and cage call number CCNA detected by the detecting means shown in FIG! 10 are applied through the input resistors R and R to the operational amplifier OA which is provided with the feedback resistor R Both of the call numbers HCN and CCNA are applied to the comparators CM5 and CM6 in which they are compared with reference voltages V,, and V set by the resistors RV, and RV If the sum of both call numbers is below a predetermined value, none of the comparators CM5 and CM6 is energized and the NOT circuits PNl and PNl produce signals N l and N2 respectively. When the sum of the calls reaches a first predetermined value, the comparator CM5 produces an output, de-energizing the NOT circuit PNl which stop producing signal N1. Further, when said sum reaches a second predetermined value, the comparator CM6 also produces an output, stopping the production of signal N2.

Assume now that the provisional position of car A in its upward is at the eighth floor and that of a preceding car downward at the fifth floor. Then the provisional position signal f8Ua is produced,-causing the OR circuits O8Ua, O9Ua and O10Da to produce an output. If, however, there are few calls from floors and from within cage A, signals N1 and N2 are presented and hence the AND circuits A9Da2 and A8Da3 both produce an output, causing also the OR circuits O9Da and O8Da to produce an output. Since car A is in upward travel, the signal STPA is produced. Under these conditions, if up calls from any of the eighth to ninth floors or down calls from the eighth to 10th floors are registered, car A responds to such hall calls. For example, if there is a down call from the 10th floor, the AND circuit A10Dal is energized, thereby setting the memory element Ml0Da. Then, car A begins to decelerate and the relay R10Da is energized, lighting the hall indicator L10Da installed at the 10th floor landing to inform waiting passengers that car A is going to stop at the 10 th floor. With the deceleration of car A, the signal S l0Da is applied to the memory element Ml0Da to reset it for the next operation. In this case, if there is a down hall call HC7D issued from the seventh floor, that call might have to be served by car A since it is a forward hall call for car A but a backward hall call for the preceding car. In this embodiment of the invention, however, the floors to be served by car A are limited to the predetermined fifth floors. Incidentally,

as long as car A stays at a floor, no memory element is energized, since the signal STPA is not produced.

Now, let us consider the case in which car A set for upward and staying at the fourth floor is at the provisional position of the eighth floor because of the succeeding car that has approached. An up call registered from the eighth floor and a down call registered from the lOth floor cause the signals HCSU and I-IC10D to be produced as shown in FIG. 9. Although the floors from which said hall calls are issued are to be covered by car A, signal STPA is not produced since car A is not in motion. Accordingly memory element M 8Ua and M lDa is not set. ln other words, car A, while staying at a given floor, has the choice of serving or preventing from responding to ahall call from its service area. This is to compensate for variations in the space relationship between cars which might be caused while car A is not in motion.

In the next place, assume that while car A is stopped, the succeeding car has come nearer and the provisional position of car A is advanced to the ninth floor. When car A starts running again, two inputs are applied to the AND circuit A 8Ua1, but the memory element, M8Ua is 7 not energized as the OR circuit O8Ua is de-energized. That is to say, car A no longer responds to'the hall call signal HC8U. However, since the OR circuit Q10Da continues to produce an output, the AND circuit A10Dal is energized, setting the memory element M10Da for response to the down call from the 10th floor. The energization of relay RlODa causes the contact R10Dal as shown in FIG. 6 to be closed and the hall indicator L10Dato be lit announcing that car A is stopping at the 10th floor.

As is evident from the above description, limiting the response to hall calls issued from its service area while a car is not in motion is an effective'measure of maintaining a reasonable space between cars. In this way, a preceding caris preventedfrom responding to a hall call from the floors which have been excluded, from the service area of that car due to a succeeding car approaching, thereby keeping the interval from the succeeding car further shortened. Those hall calls (inzsaid example, HC8U) which have not been served by the preceding car are, of course, responded to by the succeeding car.

The service area or the number of floors to be served, which is five in the foregoing example with both signals N1 and N2 on, can be varied by controlling these signals. As mentioned earlier, signal N1 stops being produced when the sum of the hall call number HCN and cage call number CCNA exceeds a predetermined value. As a result, the AND circuits A1Ua2 to A9Ua2 and Al0Da2 to A2Da2 remain without producing any outputs, whereby the service area for each car is made four floors. A further increase in the number of hall calls results in the stopping of signal N2 also, which keeps the AND circuits A1Ua3 to A9Ua3 and A10Da3 to A2Da3 de-energized and as a result the service area of each car becomes three floors from its provisional position. In the manner above explained, with an increase in traffic, the space between cars is maintained at a reasonable space by limiting the number of floors served in response to hall calls.

As mentioned above, when the distance between the position signal for a preceding car and that for a succeeding car is shortened, the provisional position signal for the preceding car is advanced in such a manner as to neglect forward hall calls from specified floors before the position indicated by the position signal for the car. Therefore, the succeeding car is prevented ,from coming too near the preceding car, if the preceding car has many hall calls to be served. Furthermore, since the physical position of each car is set in advance of the actual position thereof in consideration of its running speed, it is not necessary'to provide a specialdevice for deciding whether the car is ready for response or not and therebythe controlling device can be simplified.

What'we claim is: i i 3 A L'An elevator control system for controlling a pluralityof elevator cars serving a plurality of floor landings comprising:

-' first means for generating a positive signal related to the position of each car "space detector means responsive to the position signals generated by first means for generating a space signal for each respective elevator car indicating the spacing between the respective car and the car immediately succeeding that car,

"position advancing means for generating a provi- "sional position signal representing a provisional position ahead of the actual position of the respective car when said space signal is less than a prescribed value, andservice decision means responsive to the provisional position signals of all of said 'cars for generating a control signal enabling response to hall calls on a selected basis to maintain a predetermined relative positioning of all of said cars by limiting the response of each respective elevator car to hall calls from floors ahead of the provisional position of that car.

2. An elevator control system according to claim 1 further cdmprising:

space decision rneans responsive to said space signal for generating anadjusting signal when said space signal differs from a standard value, said adjusting signal being applied to said position advancing means for determining said provisional position 7 signal. v

3. An'elevator control system according to claim 1 wherein said service decision means includes means for controlling the respective car to respond only to those hall calls from specified floors ahead of said provisional position. I

4. An elevator control system according to claim 1 further comprising means for temporarily restraining the respective car from responding to hall calls more than two floors ahead of the provisional position except for the one from the nearest forward floor when said hall calls have been registered within a predetermined period of time.

5. An elevator control system according to claim 4 further comprising means for informing said nearest forward floor of the expected arrival of said respective car and for temporarily preventing the other floors from being informed of service when the response of said respective car to hall calls from said other floors are restrained.

6. An elevator control system according to claim 4 further comprising means for disenabling said temporary restraining means when said respective car is decelerated for service in response to a hall call.

7. An elevator control system according to claim 2 wherein said space detector means comprises a plurality of space detecting stages corresponding to the respective floors to be serviced by said elevatorcars and each including an inhibit circuit having a set input and an inhibit input, a first OR gate connected to said set input and a second OR gate connected to said inhibit input, said first OR gate receiving the positive position signal for one of said cars for the associated floor and the output of the inhibit circuit of the adjacent higher order stage, said second OR gate receiving the positive position signals of the other cars for the associated floor,-the outputs of the inhibit circuits of each stage being connected through respective resistors to one side of a common resistor the other side of which is connected to ground.

8. An elevator control system according to claim 7 wherein a single space detecting stage is provided for the terminal floors to be serviced and two spacedetecting stages are provided for each of the floors intermediate said terminal floors corresponding to the up and down directions of movement of the cars, respectively, said space detecting stages being connected in a closed chain from the outputs of said inhibit circuits to the inputs of said first OR gates in the sequence of movement of a car in both up and down directions.

. 9. An elevator control system according to claim 7 wherein said position advancing device includes a plurality of AND gates in groups of equal number, an individual OR gate connected to the outputs of each group of AND gates providing the respective provisional position signals, each AND gate receiving a positive position signal for one car associated with a single floor and an adjusting signal from said space division means, each group of AND gates being associated with a consecutive group of floors which overlap with adjacent groups.

10; An elevator control system according to claim 9 wherein said service decision means includes a plurality of service indicating stages corresponding to the respective floors to be serviced and each including an inhibit circuit having a set input and an inhibit input, a first OR gate connected to said set input and a second OR gate connected to said inhibit input, said first OR gate receiving the provisional position signal for one of said cars for the associated floor and the output of the inhibit circuit of the adjacent lower order stage, said second OR gate receiving the provisional position signals of the other cars for the associated floor, a plurality of AND gates each having an input connected to the output of one of said inhibit circuits and an input receiving a hall call signal for the floor associated with the particular service indicating stage, the outputs of said AND gates serving as said elevator car control signals.

1 1. An elevator control system according to claim 10 wherein a single service indicating stage is provided for the terminal floors to be serviced and two service indicating stages are provided for each of the floors intermediate said terminal floors corresponding to the up and down directions of movement of the cars, respectively, said service indicating stages being connected in a closed chain from the outputs of said inhibit circuits to the inputs of said first OR gates thereof in the sequenceof movement of a car in both up and down directions.

12. An elevator control system according to claim 10 wherein said service decision means further includes a plurality of memory circuits each having a set input and an inhibit input, each AND gate of the respective ser vice indicating stages being connected to the set input of one memory circuit, a third OR gate connected to the outputs of all of said memory circuits, a delay circuit connected to the output of said third OR gate and a NOT circuit connected between said delay circuit, an input of each of said AND gates, and resetting means responsive to a deceleration signal from the associated car for resetting said memory circuits via the inhibit input thereof.

Claims

1. An elevator control system for controlling a plurality of elevator cars serving a plurality of floor landings comprising: first means for generating a positive signal related to the position of each car, space detector means responsive to the position signals generated by first means for generating a space signal for each respective elevator car indicating the spacing between the respective car and the car immediately succeeding that car, position advancing means for generating a provisional position signal representing a provisional position ahead of the actual position of the respective car when said space signal is less than a prescribed value, and service decision means responsive to the provisional position signals of all of said cars for generating a control signal enabling response to hall calls on a selected basis to maintain a predetermined relative positioning of all of said cars by limiting the response of each respective elevator car to hall calls from floors ahead of the provisional position of that car.

2. An elevator control system according to claim 1 further comprising: space decision means responsive to said space signal for generating an adjusting signal when said space signal differs from a standard value, said adjusting signal being applied to said position advancing means for determining said provisional position signal.

3. An elevator control system according to claim 1 wherein said service decision means includes means for controlling the respective car to respond only to those hall calls from specified floors aHead of said provisional position.

7. An elevator control system according to claim 2 wherein said space detector means comprises a plurality of space detecting stages corresponding to the respective floors to be serviced by said elevator cars and each including an inhibit circuit having a set input and an inhibit input, a first OR gate connected to said set input and a second OR gate connected to said inhibit input, said first OR gate receiving the positive position signal for one of said cars for the associated floor and the output of the inhibit circuit of the adjacent higher order stage, said second OR gate receiving the positive position signals of the other cars for the associated floor, the outputs of the inhibit circuits of each stage being connected through respective resistors to one side of a common resistor the other side of which is connected to ground.

8. An elevator control system according to claim 7 wherein a single space detecting stage is provided for the terminal floors to be serviced and two space detecting stages are provided for each of the floors intermediate said terminal floors corresponding to the up and down directions of movement of the cars, respectively, said space detecting stages being connected in a closed chain from the outputs of said inhibit circuits to the inputs of said first OR gates in the sequence of movement of a car in both up and down directions.

9. An elevator control system according to claim 7 wherein said position advancing device includes a plurality of AND gates in groups of equal number, an individual OR gate connected to the outputs of each group of AND gates providing the respective provisional position signals, each AND gate receiving a positive position signal for one car associated with a single floor and an adjusting signal from said space division means, each group of AND gates being associated with a consecutive group of floors which overlap with adjacent groups.

11. An elevator control system according to claim 10 wherein a single service indicating stage is provided for the terminal floors to be serviced and two service indicating stages are provided for each of the Floors intermediate said terminal floors corresponding to the up and down directions of movement of the cars, respectively, said service indicating stages being connected in a closed chain from the outputs of said inhibit circuits to the inputs of said first OR gates thereof in the sequence of movement of a car in both up and down directions.

12. An elevator control system according to claim 10 wherein said service decision means further includes a plurality of memory circuits each having a set input and an inhibit input, each AND gate of the respective service indicating stages being connected to the set input of one memory circuit, a third OR gate connected to the outputs of all of said memory circuits, a delay circuit connected to the output of said third OR gate and a NOT circuit connected between said delay circuit, an input of each of said AND gates, and resetting means responsive to a deceleration signal from the associated car for resetting said memory circuits via the inhibit input thereof.

18. An elevator control system according to claim 9 wherein said service decision means includes a plurality of service indicating stages corresponding to the respective floors to be serviced and each including an inhibit circuit having a set input and an inhibit input, a first OR gate connected to said set input and a second OR gate connected to said inhibit input, said first OR gate receiving the provisional position signal for one of said cars for the associated floor and the output of the inhibit circuit of the adjacent lower order stage, said second OR gate receiving the provisional position signals of the other cars for the associated floor, a plurality of AND gates each having an input connected to the output of one of said inhibit circuits and an input receiving a hall call signal for the floor associated with the particular service indicating stage, the outputs of said AND gates serving as said elevator car control signals.